I feel you so much. I used to have extreme existential anxiety so much so that sometimes I couldnāt sleep. Lately this has changed I canāt exactly pin point why but thereās a couple of thoughts that calm me down. Firstly we as humans always think we have it all figured out and we know what happens after but even if you are atheist you donāt know whatās going to happen and probably never will. For me the fear that thereās just nothing after death just lights out was scary but how would we actually know this is going to happen, we see ourselves as omniscient although there are so many things that we will probably never discover or understand.
You have to learn how to live with the uncontrollability and uncertainty of it. Secondly time passes anyways and death is inevitable no matter what you do. If I worry or if I donāt worry Iām going to die, might as well enjoy my time. Life is absurd. I think my existential dread calmed down a bit when I started reading Camus. Maybe life doesnāt have to have a meaning. If youāre interested in philosophy i definitely recommend reading Camus or thereās also youtube videos that summarise his Philosophy. I really liked āthe fallā and āthe strangerā and am currently reading āthe myth of Sisyphusā. Maybe some of these things resonate with you :))